[labnetwork] Question: use of gas alarm logic to prevent building evacuations on silane bottle changes...

[Iulian Codreanu]

Hi Ian.

I use logic in my HGMS system provided by Honeywell. If Hi alarm is 
tripped inside of a toxic gas cabinet AND the cabinet lost its exhaust I 
push more air into the gas room to dilute anything that might escape.

iulian Codreanu, Ph.D.
Director, Penn NanoFab
200 South 33rd Street
Room 305 Moore Bldg
Philadelphia, PA 19104-6314
P: 215-898-9308
F: 215-573-2068
www.seas.upenn.edu/~nanofab

On 5/5/2011 8:44 PM, Ian Harvey wrote:
> Dear Labnetwork,
>
> *Question:*
> How to prevent spurious gas/silane alarms (e.g., from cylinder change
> burps) from unnecessarily evacuating an entire building?
>
> *Background:*
> We recently had a very brief burst/decay of silane associated with the
> removal of the dust cap in preparation for installing a new silane
> cylinder. The burst was captured by our gas alarm as a single "spike"
> that exceeded the level-2 alarm threshold (10 PPM) for 3 seconds and
> decayed back to below level 1 (5 PPM) after 12 seconds (peak was 19
> PPM). However, the fire alarm was triggered, the entire engineering
> building was evacuated for 20 minutes, and six fire trucks showed up.
>
> This cylinder was 13 months old, 1 month past its expiration date. The
> cylinder was chained and strapped into position inside the gas cabinet
> when the dust cap was removed. At present, we feel it is best to
> evacuate the building, since our old lab is in a B-class occupancy area.
> However, in our new facility, our silane will be behind a 2 hr firewall
> in a special gas room, attached to the single-story fab wing and 50
> yards from (but still attached to) the multi-story research tower. We
> are looking for more robust system-level solutions limiting unnecessary
> evacuation of the research tower in our new facility.
>
> *Approaches:* Aside from procedural approaches like "Don't use expired
> cylinders", and "Open dust caps very slowly", has anyone attempted to
> use alarm logic in their HPM system, such as: "<<If>> the alarm
> originates in the gas box <<and>> room air sensor is below threshold...
> or variations on timing between sense and decay to stage the triggering
> of different alarm levels??
>
> How do others handle this situation in your respective labs?
>
> Thank you in advance for your inputs!
>
> --Ian
>
> ********************************************
> Ian R. Harvey, Ph.D.
> Associate Director, Utah nanofab
> College of Engineering / University of Utah
>
> Research Associate Professor
> Department of Mechanical Engineering
> Adjunct Associate Professor
> Department of Electrical & Computer Engineering
> 2232 MEB
>
> mail to suite 2110 MEB, 50 S. Central Campus Drive
> Salt Lake City, Utah 84112-9011
> 801/585-6162 (voicemail)
> 801/581-5676 (lab main number)
> www.nanofab.utah.edu <http://www.nanofab.utah.edu>
>
>
>
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